avformat/udp: redesign threaded udp tx code
This fixes partially completed send() Avoids holding the mutex during send() fixes race conditions in error handling removes copied non thread specific blocking code Fixes deadlocks on closure Fixes data loss on closure Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer
parent
413c842a69
commit
9b7a8bddac
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@ -29,6 +29,7 @@
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#include "avformat.h"
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#include "avio_internal.h"
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#include "libavutil/avassert.h"
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#include "libavutil/parseutils.h"
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#include "libavutil/fifo.h"
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#include "libavutil/intreadwrite.h"
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@ -93,6 +94,7 @@ typedef struct UDPContext {
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AVFifoBuffer *fifo;
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int circular_buffer_error;
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int64_t packet_gap; /* delay between transmitted packets */
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int close_req;
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#if HAVE_PTHREAD_CANCEL
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pthread_t circular_buffer_thread;
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pthread_mutex_t mutex;
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@ -545,30 +547,6 @@ end:
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return NULL;
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}
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static void do_udp_write(void *arg, void *buf, int size) {
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URLContext *h = arg;
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UDPContext *s = h->priv_data;
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int ret;
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if (!(h->flags & AVIO_FLAG_NONBLOCK)) {
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ret = ff_network_wait_fd(s->udp_fd, 1);
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if (ret < 0) {
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s->circular_buffer_error = ret;
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return;
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}
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}
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if (!s->is_connected) {
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ret = sendto (s->udp_fd, buf, size, 0,
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(struct sockaddr *) &s->dest_addr,
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s->dest_addr_len);
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} else
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ret = send(s->udp_fd, buf, size, 0);
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s->circular_buffer_error=ret;
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}
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static void *circular_buffer_task_tx( void *_URLContext)
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{
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URLContext *h = _URLContext;
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@ -576,41 +554,67 @@ static void *circular_buffer_task_tx( void *_URLContext)
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int old_cancelstate;
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_cancelstate);
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pthread_mutex_lock(&s->mutex);
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if (ff_socket_nonblock(s->udp_fd, 0) < 0) {
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av_log(h, AV_LOG_ERROR, "Failed to set blocking mode");
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s->circular_buffer_error = AVERROR(EIO);
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goto end;
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}
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for(;;) {
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int len;
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const uint8_t *p;
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uint8_t tmp[4];
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pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &old_cancelstate);
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av_usleep(s->packet_gap);
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_cancelstate);
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pthread_mutex_lock(&s->mutex);
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len=av_fifo_size(s->fifo);
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while (len<4) {
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if (s->close_req)
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goto end;
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if (pthread_cond_wait(&s->cond, &s->mutex) < 0) {
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goto end;
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}
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len=av_fifo_size(s->fifo);
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}
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av_fifo_generic_peek(s->fifo, tmp, 4, NULL);
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av_fifo_generic_read(s->fifo, tmp, 4, NULL);
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len=AV_RL32(tmp);
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if (len>0 && av_fifo_size(s->fifo)>=len+4) {
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av_fifo_drain(s->fifo, 4); /* skip packet length */
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av_fifo_generic_read(s->fifo, h, len, do_udp_write); /* use function for write from fifo buffer */
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if (s->circular_buffer_error == len) {
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/* all ok - reset error */
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s->circular_buffer_error=0;
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av_assert0(len >= 0);
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av_assert0(len <= sizeof(s->tmp));
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av_fifo_generic_read(s->fifo, s->tmp, len, NULL);
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pthread_mutex_unlock(&s->mutex);
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pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &old_cancelstate);
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p = s->tmp;
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while (len) {
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int ret;
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av_assert0(len > 0);
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if (!s->is_connected) {
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ret = sendto (s->udp_fd, p, len, 0,
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(struct sockaddr *) &s->dest_addr,
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s->dest_addr_len);
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} else
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ret = send(s->udp_fd, p, len, 0);
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if (ret >= 0) {
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len -= ret;
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p += ret;
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} else {
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ret = ff_neterrno();
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if (ret != AVERROR(EAGAIN) && ret != AVERROR(EINTR)) {
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s->circular_buffer_error = ret;
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return NULL;
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}
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}
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}
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pthread_mutex_unlock(&s->mutex);
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av_usleep(s->packet_gap);
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_cancelstate);
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pthread_mutex_lock(&s->mutex);
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}
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end:
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@ -1055,7 +1059,6 @@ static int udp_write(URLContext *h, const uint8_t *buf, int size)
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*/
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if (s->circular_buffer_error<0) {
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int err=s->circular_buffer_error;
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s->circular_buffer_error=0;
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pthread_mutex_unlock(&s->mutex);
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return err;
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}
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@ -1093,13 +1096,26 @@ static int udp_close(URLContext *h)
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{
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UDPContext *s = h->priv_data;
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#if HAVE_PTHREAD_CANCEL
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// Request close once writing is finished
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if (s->thread_started && !(h->flags & AVIO_FLAG_READ)) {
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int ret;
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pthread_mutex_lock(&s->mutex);
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s->close_req = 1;
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pthread_cond_signal(&s->cond);
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pthread_mutex_unlock(&s->mutex);
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}
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#endif
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if (s->is_multicast && (h->flags & AVIO_FLAG_READ))
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udp_leave_multicast_group(s->udp_fd, (struct sockaddr *)&s->dest_addr,(struct sockaddr *)&s->local_addr_storage);
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closesocket(s->udp_fd);
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#if HAVE_PTHREAD_CANCEL
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if (s->thread_started) {
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int ret;
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pthread_cancel(s->circular_buffer_thread);
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// Cancel only read, as write has been signaled as success to the user
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if (h->flags & AVIO_FLAG_READ)
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pthread_cancel(s->circular_buffer_thread);
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ret = pthread_join(s->circular_buffer_thread, NULL);
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if (ret != 0)
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av_log(h, AV_LOG_ERROR, "pthread_join(): %s\n", strerror(ret));
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